Effects of leaf age during drought and recovery on photosynthesis, mesophyll conductance and leaf anatomy in wheat leaves

Abstract

Summary statement: Mesophyll conductance (gm) was negatively correlated with wheat leaf age but was positively correlated with the surface area of chloroplasts exposed to intercellular airspaces (Sc). The rate of decline in photosynthetic rate and gm as leaves aged was slower for water-stressed than well-watered plants. Upon rewatering, the degree of recovery from water-stress depended on the age of the leaves, with the strongest recovery for mature leaves, rather than young or old leaves. Diffusion of CO2 from the intercellular airspaces to the site of Rubisco within C3 plant chloroplasts (gm) governs photosynthetic CO2 assimilation (A). However, variation in gm in response to environmental stress during leaf development remains poorly understood. Age-dependent changes in leaf ultrastructure and potential impacts on gm, A, and stomatal conductance to CO2 (gsc) were investigated for wheat (Triticum aestivum L.) in well-watered and water-stressed plants, and after recovery by re-watering of droughted plants. Significant reductions in A and gm were found as leaves aged. The oldest plants (15 days and 22 days) in water-stressed conditions showed higher A and gm compared to irrigated plants. The rate of decline in A and gm as leaves aged was slower for water-stressed compared to well-watered plants. When droughted plants were rewatered, the degree of recovery depended on the age of the leaves, but only for gm. The surface area of chloroplasts exposed to intercellular airspaces (Sc) and the size of individual chloroplasts declined as leaves aged, resulting in a positive correlation between gm and Sc. Leaf age significantly affected cell wall thickness (tcw), which was higher in old leaves compared to mature/young leaves. Greater knowledge of leaf anatomical traits associated with gm partially explained changes in physiology with leaf age and plant water status, which in turn should create more possibilities for improving photosynthesis using breeding/biotechnological strategies.

Evaluation of Quinoa Varieties for Adaptability and Yield Potential in Low Altitudes and Correlation with Agronomic Traits

“…Notably, there is a significant negative correlation between yield and the decrease in green leaf area per plant after anthesis. The reduction in green leaf area decrement after anthesis, coupled with an increase in net photosynthetic rate, led to enhanced dry matter accumulation and increased grain yield, aligning with previous research [43,44].…”

Differential Physiological Responses to Different Drought Durations among a Diverse Set of Sugarcane Genotypes

“…Acclimation of younger SD2 plants to evolving water deficit stress potentially also helped slow the decline in RWC, whereas SD1 plants had already established a large leaf surface area for transpirational water loss at 3 MAT (Figure 6). Similar age-dependent responses of physiological parameters to water deficits have been reported in wheat [38] and several Mediterranean species [39], whereby leaf gas exchange parameters decreased more rapidly in older leaves and plants than in young seedlings in response to drought. Previous field and greenhouse studies with sugarcane have also reported significant drought-induced reductions in key physiological and agronomic parameters, ultimately leading to reductions in yield components [5,8,12,16,18,21,27,40].…”

High-Frequency Mapping of Downward Shortwave Radiation from GOES-R Using Gradient Boosting

“…The ability of DSR ALIVE to capture observed short-term variations holds significant value for various applications. For instance, monitoring rapid phenomena like heatwaves [63], [64], wildfires [65], [66], [67], water stresses and flash droughts [68], [69], and other fast-changing environmental events often necessitates high-frequency data. Similarly, studies investigating the carbon cycle or other processes sensitive to short-term fluctuations in solar radiation benefit from high-resolution DSR data [8], [70], [71], [72].…”